Fire is often used for decorative or entertainment effects, for example, in fire pits or theatrical displays. Sometimes, bursts of flame may be triggered in conjunction with music or other inputs. Examples are disclosed, for example, in U.S. Pat. Nos. 5,890,485; 6,413,079; and U.S. Pat. No. 8,823,714 (Thielvoldt). Thielvoldt's “Music-Reactive Fire Display” utilizes a digital signal processor programmed to analyze a music input signal and generate a “visualization signal” output to control a flame display responsive to the music. That type of system requires relatively expensive and complicated digital components and software. The need remains for simpler, less expensive, yet effective methods and circuits to control a fire display responsive to music, so that the music and fire display together form an attractive and compelling audio-visual experience. The disclosure that follows solves this and other problems.